Generator and fan

ABSTRACT

An improved generator fan serves to draw air into the generator through an inlet in the generator housing, pass the air through the rotor and stator, and direct the air out openings in the generator housing. The fan of the present invention includes a disc and at least one multi-directional blade extending from the disc. The multi-direction blade includes a leading segment extending from the disc between a first radius measured from the axis of rotation and a second radius, the leading segment including a leading edge extending from the disc at an angle of about ninety degrees from the disc, the leading segment extending from the disc with an increasing angle along the length of the leading segment; and a trailing segment extending from the disc between the second radius and a third radius measured from the axis of rotation, the third radius being greater than the second radius and the trailing segment extending from the disc with an angle having a rate of change different than the leading segment.

TECHNICAL FIELD

The present invention relates to an improved generator and fan. Morespecifically, the invention provides a generator utilizing an improvedrotor fan.

BACKGROUND OF THE INVENTION

Without a generator, the electrical load of a vehicle would quicklydrain a fully charged battery. In a vehicle, a generator producingalternating current (AC), known as an alternator, is often mounted atthe front of the engine and is linked to the engine crankshaft pulley bya drive belt. When the engine turns the drive belt, the drive belt turnsa shaft in the alternator, and current is generated. Current is producedin an alternator when a wire intercepts a magnetic field. In analternator, it is the wire, in coiled form, that is held stationary andthe magnetic field is turned so that the magnetic field passes throughthe wire. Thus, alternators include a stationary part, the stator, and arotating part, the rotor.

The stator may include stationary coils or slotted pins or segments thatsurround a rotor. As the rotor is turned by the car engine, thealternating magnetic field created by the rotor is intercepted by thestationary coils, pins or segments, and current flows through the statorfirst in one direction, then in the other, resulting in alternatingcurrent. As the rotor is turned, air flow within the assembly willproduce noise in the audible range that will emanate from the alternatorassembly.

The rotor includes an electromagnet that is magnetized by current fromthe battery. The electromagnet may include slip rings, rotor windings,and north and south pole members surrounding the rotor windings. Currentfrom the battery flows through the slip rings to the rotor windings.North and south pole members have pole claws shaped like interlockingteeth surrounding the rotor windings. The north and south pole memberscreate an alternating magnetic field as the rotor turns.

A housing surrounds the rotor and stator assembly. The stator is fixedrelative to the housing and the rotor shaft is rotatably mountedrelative to the housing. Because the battery and electrical componentsin the car work on direct current (DC), the AC output of the alternatormust be converted to DC. This is done with rectifiers which pass currentin one direction only. The components within the alternator produce heatand, in addition, the alternator operates under high under hoodtemperatures. To reduce the amount of heat in the alternator, a fan isincluded in the alternator assembly as seen in reference to U.S. Pat.No. 4,549,103 to Shega, entitled Multi-Path Cooling in an AC Generatorfor a Vehicle.

The fan may be placed inside or outside of the housing to increaseairflow between the rotor and stator and to increase airflow throughopenings in the housing. The fan blades may face inward toward thecentral portion of the alternator or outward away from the centralportion of the alternator. Rotation of the fan helps increase airflowwithin the alternator and helps to reduce heat within the alternator,but also increases the amount of audible noise emanating from thealternator assembly, an undesirable feature particularly from the pointof view of the operator of the vehicle in which the alternator ismounted.

The noise produced by an alternator depends, at least in part, on thedesign of the alternator fan blades. Alternator fans with straight fanblades having an inside angle of more than ninety degrees from the baseof the fan, tend to produce less noise, but undesirably also provideless airflow. Alternator fans with straight fan blades at ninety degreesfrom the base of the fan produce more airflow, but undesirably morenoise. To improve the airflow resulting from a fan with swept outblades, the length of the blade can be increased but this undesirablyreduces the number of blades that can be included on a single fan. Otherdesigns have incorporated alternating blades, some blades at ninetydegrees and other blades having an inside angle of more than ninetydegrees. However, the limitations associated with each type of blade arenot entirely overcome by known designs. The present invention overcomesthese problems to provide an alternator incorporating an improved fan,resulting in an alternator with reduced noise, improved tonality andimproved radial and axial cooling airflow.

SUMMARY OF INVENTION

The present invention provides an improved generator with improved soundquality and reduced noise level, and also provides improved airflowthrough the generator, improving cooling of the generator components. Animproved generator fan serves to draw air into the generator through aninlet in the generator housing, pass the air through the rotor andstator, and direct the air out openings in the generator housing. Thefan of the present invention includes a disc adapted to be centrallymounted on a shaft that represents an axis about which the fan rotates.According to the present invention, at least one multi-directional bladeextends from the disc. The multi-direction blade includes a leadingsegment extending from the disc between a first radius measured from theaxis of rotation and a second radius measured from the axis of rotation,the leading segment including a leading edge extending from the disc atan angle of about ninety degrees from the disc, the leading segmentextending from the disc with a swept out shape starting at the leadingedge and extending from the disc with an increasing angle along thelength of the leading segment. A trailing segment extends from the discbetween the second radius and a third radius measured from the axis ofrotation, the third radius being greater than the second radius and thetrailing segment extending from the disc with an angle having a rate ofchange different than the leading segment.

An improved generator having the inventive fan exhibits improvedtonality and a reduced noise level. The resulting generator alsoprovides improved cooling. Other aspects of the present invention areprovided with reference to the figures and detailed description ofembodiments provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of an exemplary generator;

FIG. 2 illustrates a front view of an embodiment of an improvedgenerator fan;

FIG. 3 illustrates a side view of an embodiment of an improved generatorfan;

FIG. 4 illustrates an isometric view of an embodiment of an improvedgenerator fan;

FIG. 5 illustrates a front view of an embodiment of an improvedgenerator fan;

FIG. 6 illustrates a side view of an embodiment of an improved generatorfan; and

FIG. 7 illustrates an isometric view of an embodiment of an improvedgenerator fan.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a generator with improved sound qualityand reduced noise level, and also provides improved airflow through thegenerator, improving cooling of the generator components. An improvedgenerator fan serves to draw air into the generator through an inlet inthe generator housing, pass the air through the rotor and stator, anddirect the air out openings in the generator housing.

FIG. 1 illustrates an example of an exemplary generator 10 in which theimproved fan of the present invention may be used. The exemplarygenerator includes a stator assembly 15 surrounding a rotor assembly 20.The rotor assembly 20 includes a shaft 21 supporting all rotatingmagnetic structures including conventional pole-members 16A and 16B, arotor core 17 and a field coil 18 wound upon bobbin 12. Additionally,all other non-magnetic circuit rotating structures are carried,including air circulation fans 19 and 27 located at axially oppositesides of the pole-members, and a slip ring assembly 30 located at oneextreme end of the shaft 21. The fan 27 is formed from sheet metal stockand spot welded to the pole-member 16B while fan 19 is formed from anappropriate thermoplastic material and heat staked to tower extensions(not shown) from the field coil bobbin 12. The shaft 21 is rotatablysupported within a housing 26 by a pair of bearings 23 and 22. Bearing23 is located between the slip ring assembly 30 and the fan 19. Coilleads 18A of field coil 18 are wrapped about respective posts 12A ofbobbin 12 and pass through holes 13 in fan 19. Slip ring assembly 30 ismade of a pair of copper rings 31 each having a slip ring lead 32 joinedsuch as by welding thereto. The copper rings and wires are molded into athermoset material to complete the slip ring assembly 30. Slip ringassembly 30 is pressed onto the end of rotor shaft 21 and the slip ringleads 32 are routed into channels along the shaft 21 where they arejoined, such as by twisting and welding, to the coil leads 18A of fieldcoil 18 via a joint 24. The joint 24 is then bent to the surface of thefan 19 and received in a pyramid shaped tab structure 25. The joint 24is then secured to fan 19 by ultrasonic welding of the plastic materialof the tab 25. Bearing 23 is assembled to pass over the slip ringassembly 30 to retain the lead wires 32 securely within the shaftchannels. Preferably, fan 27 of FIG. 1 is replaced by the improved fandescribed with respect to FIGS. 2-7. Other applications of the inventivefan are possible and remain within the spirit and scope of theinvention. Various embodiments of the present invention are describedherein.

FIG. 2 illustrates a front view of an embodiment of an improvedgenerator fan 110. The generator fan 110 of this embodiment is suitablefor use in an alternator such as would be used in an automobile and maybe replace either of fan 19 or fan 27, or both fan 19 and fan 27, in theexemplary generator of FIG. 1. The fan 110 of the present inventionprovides both axial and radial airflow. The fan 110 includes a disc 120adapted to be mounted on a rotor shaft having an axis 130 of rotationthat the fan 110 rotates about. According to the present invention, atleast one multi-directional blade 170 extends from the disc 120. Withrespect to a clockwise direction of rotation in this view, themulti-direction blade includes a leading segment 180. The leadingsegment 180 is defined as the portion of multi-directional blade 170extending from the disc 120 between a first radius 140 measured from theaxis 130 of rotation and a second radius 150 measured from the axis 130of rotation, the second radius 150 being greater than the first. Theleading segment 180 extends from the disc 120 with a swept out anglestarting at a leading edge having an angle of ninety degrees at thefirst radius and increasing along the length of the leading segment 180.The trailing segment 190 is defined as the portion of multi-directionalblade 170 that extends from the disc 120 between the second radius 150and a third radius 160 measured from the axis 130 of rotation, the thirdradius 160 being greater than the second radius 150. The trailingsegment 190 differs from the leading segment 180 in that the trailingsegment extends from the disc 120 at an angle having a rate of changedifferent from the leading segment 180. According to one embodiment, thetrailing segment 190 extends from the disc 120 at a fixed angle. Theamount of radial and axial flow can be adjusted by tailoring the rate ofchange of the angle of the trailing segment 190 to provide the desiredamount of flow in each direction. Flow directed radially will havegreater interaction with the stator. Flow directed axially will havegreater interaction with the rotor. The improved fan 110 providesincreased flow rates at the same time reducing noise and improvingtonality. The improved fan 110 may be formed from any of a variety ofmetals including without limitation steel. The fan 110 of thisembodiment can be formed by a punched metal process in which the entirefan 110 is formed from a single metal piece. In an alternativeembodiment, the fan 110 may be of a molded material including withoutlimitation polymer materials. The improved fan 110 provides increasedflow rates at the same time reducing noise and improving tonality.

FIG. 2 further illustrates an embodiment in which the base portion 200of the blade has an arced interface 220 with the disc 120. The fan 110may additionally include flow apertures 260 between themulti-directional blade 170 and an adjacent blade. This improves airflowon both sides of the fan 110 and helps to eliminate flow blockage.

According to the embodiment shown in FIG. 2, the fan 110 may include aplurality of overlapping multi-directional blades 170. According to theinvention, the first radius 140 is defined to be less than the secondradius 150 and the second radius 150 less than the third radius 160, asa result, the plurality of multi-directional blades 170 may overlap oneanother so that the leading segment 180 of each multi-directional blade170 begins proximal the second radius 150 of an adjacentmulti-directional blade 170. This allows for an increased number ofblades on the disc 120 and allows for blades having increased lengtheach providing increased airflow. The first radius 140 and third radius160 define a central blade angle A of about eighty degrees, and the fan110 includes eight overlapping multi-directional blades 170 distributedaround the disc 120. According to one embodiment, the multi-directionalblades 170 are uniformly distributed about the disc 120. According toone embodiment, the multi-directional blades 170 are non-uniformlydistributed around the disc 120 to reduce the level of noise created bythe airflow. According to one embodiment, angle A varies frommulti-directional blade 170 to multi-directional blade 170 on the samedisc 120 to further decrease the level of noise created by the airflow.

According to one embodiment, the upper portion 210 of themulti-directional blade 170 terminates in an outer edge 230 defined bythe outermost portion of the leading segment 180 and trailing segment190, gradually increases in distance from the disc 120 as the leadingsegment 180 extends from the first radius 140 to the second radius 150and gradually decreases in distance from the disc 120 as the trailingsegment 190 extends from the second radius 150 to the third radius 160.

According to one embodiment, the leading section 180 sweeps from theangle of about ninety degrees at the leading edge to an angle of aboutone hundred twenty degrees where the leading segment 180 meets thetrailing segment 190. This improves the flow rate in both the axial andradial direction by increasing the mount of air drawn in by the fan 110while reducing noise level. According to one embodiment, the trailingsegment extends from the disc 120 at an angle of about one hundredtwenty degrees to provide the desired ratio of radial flow and axialflow of air to cool the generator. According to one embodiment, thetrailing segment 190 extends from the disc at an angle greater thanabout one hundred twenty degrees, increasing the amount of axial airflowthrough the generator.

FIG. 3 is a side view of an embodiment of the improved generator fan 110showing the multi-directional blades 170 overlapping one another. Asseen in this view, the trailing segments 190 overlap the leadingsegments 180. The overlapping multi-directional blades 170 providebetter axial airflow than known generator fans having only bladesuniformly tilted inward. The noise level is decreased in part due toless airflow interaction with the stator. The overlappingmulti-directional blades 170 also provide smoother inlet and outletairflow as the air passes in and out of the generator. Flow apertures260 between the overlapping multi-directional blade 170 improve airflowon both sides of the fan 110 and help to eliminate flow blockage.

FIG. 4 illustrates an isometric view of an embodiment of the improvedgenerator fan 110 utilizing a multi-directional blade 170 to provideboth axial and radial airflow to a generator. The fan 110 includes adisc 120 adapted to be mounted on a generator shaft or rotor shaft andat least one multi-directional blade 170 extending from the disc 120. Inthis embodiment, at least one port 270 is included in the disc 120 todynamically balance the fan. In this embodiment, the flow aperturesbetween the multi-directional blades are enlarged relative to the flowapertures shown in FIG. 2. According to one embodiment, the leadingsection 180 sweeps from the angle of about ninety degrees at the leadingedge to an angle of about one hundred twenty degrees where the leadingsegment 180 meets the trailing segment 190. This improves the flow ratein both the axial and radial direction by increasing the mount of airdrawn in by the fan 110 while reducing noise level. According to oneembodiment, the trailing segment extends from the disc 120 at an angleof about one hundred twenty degrees to provide the desired ratio ofradial flow and axial flow of air to cool the generator. According toone embodiment, the trailing segment 190 extends from the disc at anangle greater than about one hundred twenty degrees, increasing theamount of axial airflow through the generator.

FIG. 5 illustrates a front view of an embodiment of the improvedgenerator fan 110′. The generator fan 110′ of this embodiment may beused in an alternator such as would be used in an automobile and may beused in place of fan 19 or fan 27, or both fan 19 and fan 27, in theexemplary generator of FIG. 1. The fan 110′ of the present inventionprovides both axial and radial airflow. The fan 110′ includes a disc120′ adapted to be centrally mounted on a rotor shaft which representsan axis 130′ of rotation that the fan 110′ rotates about. According tothe present invention, at least one multi-directional blade 170′ extendsfrom the disc 120′. The multi-direction blade includes a leading segment180′ extending from the disc 120′ between a first radius 140′ measuredfrom the axis 130′ of rotation and a second radius 150′ measured fromthe axis 130′ of rotation, the second radius 150′ being greater than thefirst. The leading segment 180′ extends from the disc 120′ at an angleof about ninety degrees from the disc 120′. The trailing segment 190′extends from the disc 120′ between the second radius 150′ and a thirdradius 160′ measured from the axis 130′ of rotation, the third radius160′ being greater than the second radius 150′. The trailing segment190′ extends from the disc 120′ at an angle having a rate of changedifferent than the leading segment 180′. The amount of radial and axialflow can be adjusted by tailoring the angle of the trailing segment 190′to provide the desired amount of flow in each direction. Flow directedradially will have greater interaction with the stator. Flow directedaxially will have greater interaction with the rotor. The improved fan110′ provides increased flow rates at the same time reducing noiselevels and improving tonality.

In this embodiment, the multi-directional blade 170′ is combined with atleast one straight blade 240′ having a substantially planar shape and astraight interface 250′ with the disc 120′. The straight blade 240′ hasa uniform angle from the disc 120′ along the entire length of the blade.Thus, the amount of radial and axial flow can be further adjusted bytailoring the angle of the straight blade 240′ to provide the desiredamount in combination with the affect of the multi-directional blade170′. The straight blade 240′ may be defined by a straight angle ofninety degrees, less than ninety degrees, or more than ninety degrees.Further, various combinations of straight and tilted blades may beincorporated into the improved fan 110′.

According to one embodiment, at least one flow port 260′ is included inthe fan 110′ between the multi-directional blade 170′ and an adjacentblade. This improves airflow on both sides of the fan 110′. According toone embodiment, the fan 110′ includes six multi-directional blades 170′and four uniform blades.

According to one embodiment, the leading section 180′ sweeps from theangle of about ninety degrees at the leading edge to an angle of aboutone hundred twenty degrees where the leading segment 180′ meets thetrailing segment 190′. This improves the flow rate in both the axial andradial direction by increasing the mount of air drawn in by the fan 110′while reducing noise level. According to one embodiment, the trailingsegment extends from the disc 120′ at an angle of about one hundredtwenty degrees to provide the desired ratio of radial flow and axialflow of air to cool the generator. According to one embodiment, thetrailing segment 190′ extends from the disc at an angle greater thanabout one hundred twenty degrees, increasing the amount of axial airflowthrough the generator.

In the embodiment of FIG. 5, an outer edge 230′, defined by theoutermost portion of the upper portion 210′ of the leading segment 180′and trailing segment 190′ has a substantially constant distance from thedisc 120′ providing a blade with a substantially uniform height alongthe length of the blade. FIG. 6 is a side view of the improved generatorfan 110′ of FIG. 5.

FIG. 7 illustrates an isometric view of an improved generator fan 110′utilizing a multi-directional blade 170′ to provide both axial andradial airflow to a generator. The fan 110′ includes a disc 120′ adaptedto be mounted on a generator shaft and at least one multi-directionalblade 170′ extending from the disc 120′. As seen in this view, the baseof the multidirectional blade may have an arced interface 220′ with thedisc 120′. According to one embodiment of the invention, the anglebetween the second radius 150′ and third radius 160′ is defined as acentral blade angle A′ of about 8 degrees and the blades are distributedon the disc 120′ without overlapping an adjacent blade. According to oneembodiment, the fan 110′ includes six multi-directional blades 170′ andfour uniform blades distributed on the disc 120′.

The improved fan described herein can be mounted axially inward of thehousing with the blades extending outward. In an alternative embodiment,the fan can be mounted axially outward of the housing with the bladesextending axially inward. More than one fan 110 may be employed in asingle generator.

The invention provided herein allows more flexibility to tune a fan 110design to provide airflow for a given application according to thedesired noise level, tonality, axial airflow and radial airflow. Whilethe present invention has been described with reference to exemplaryembodiments, a variety of embodiments may be produced utilizing theapparatus and process described herein. Modifications and variations inthe invention will be apparent to those skilled in the art in light ofthe foregoing description. It is therefore contemplated that theappended claims and their equivalents will embrace any suchalternatives, modifications and variations as falling within the scopeof the present invention.

1. A generator fan, comprising: a disc adapted to be centrally mountedperpendicular to an axis of rotation and at least two multi-directionalblades extending from the disc, the multi-directional blades including:a leading segment extending from the disc between a first radiusmeasured from the axis of rotation and a second radius measured from theaxis of rotation, the leading segment including a leading edge extendingfrom the disc at an angle of about ninety degrees from the disc, theleading segment extending from the disc with a swept out shape startingat the leading edge and extending from the disc with an increasing anglealong the length of the leading segment; and a trailing segmentextending from the disc between the second radius and a third radiusmeasured from the axis of rotation, the third radius being greater thanthe second radius and the trailing segment extending from the disc withan angle having a rate of change different than the leading segment;wherein said multi-directional blades further include an arced interfacewith said disc; and wherein said multi-directional blades overlap oneanother so that the leading segment begins proximal the second radius ofan adjacent multi-directional blade.
 2. A generator comprising: agenerator shaft defining an axis of rotation; a fan including a discmounted on the shaft and at least one multi-directional blade extendingfrom the disc, the multi-directional blade including: a leading segmentextending from the disc between a first radius measured from the axis ofrotation and a second radius measured from the axis of rotation, theleading segment including a leading edge extending from the disc at anangle of about ninety degrees from the disc, the leading segmentextending from the disc with a swept out shape starting at the leadingedge and extending from the disc with an increasing angle along thelength of the leading segment; a trailing segment extending from thedisc between the second radius and a third radius measured from the axisof rotation, the third radius being greater than the second radius andthe trailing segment extending from the disc with an angle having a rateof change different than the leading segment; at least one uniform bladehaving a uniform angle from the disc; and a flow port between saidmulti-directional blade and an adjacent blade.